Hi,
thanks for your work on a helgrind replacement. Such a tool is a great help
for us.
I have tested thrcheck from revision 7044 with the attached program. Here are
some problems I found:
1. The concurrent writes on line 72 are not protected by a mutex (uncommented
above and below). Thrcheck does not flag this error on my i386 and x86_64
machines.
2. There is no race-condition for the writes in line 92. However the i386
version of thrcheck flags an error here.
3. The x86_64 version only shows that one thread is started. Threads 3 -- 9
are not shown.
4. The i386 version flags a possible race condition in line 41. In my opinion
there is none.
Greetings
Christoph
#include <iostream>
#include <vector>
extern "C" {
#include <pthread.h>
}
pthread_mutex_t job_mutex = PTHREAD_MUTEX_INITIALIZER;
pthread_mutex_t odd_mutex = PTHREAD_MUTEX_INITIALIZER;
pthread_mutex_t even_mutex = PTHREAD_MUTEX_INITIALIZER;
pthread_cond_t job_cond = PTHREAD_COND_INITIALIZER;
static int jobs_completed = 0;
static int const NUM_THREADS = 8;
class Job {
public:
virtual void run() = 0;
};
Job * work[NUM_THREADS] = {NULL, NULL};
extern "C" void * start(void *) {
while (true) {
pthread_mutex_lock(&job_mutex);
Job * job = NULL;
while (true) {
for (int i = 0; i < NUM_THREADS; ++i) {
if (work[i] != NULL) {
job = work[i];
work[i] = NULL;
break;
}
}
if (job) break;
pthread_cond_wait(&job_cond, &job_mutex);
}
pthread_mutex_unlock(&job_mutex);
job->run();
pthread_mutex_lock(&job_mutex);
++jobs_completed;
pthread_cond_broadcast(&job_cond);
pthread_mutex_unlock(&job_mutex);
}
return NULL;
}
struct Data {
Data() : counter(0) {}
int counter;
};
class Loop : public Job {
public:
Loop(std::vector<Data *> & vec) : vec(vec) {}
virtual void run() {
for (std::size_t i = 0; i < vec.size(); ++i) {
if (i % 2 == 0) {
pthread_mutex_lock(&even_mutex);
vec[i]->counter++;
pthread_mutex_unlock(&even_mutex);
} else {
// pthread_mutex_lock(&odd_mutex);
vec[i]->counter++;
// pthread_mutex_unlock(&odd_mutex);
}
}
}
private:
std::vector<Data *> & vec;
};
class Jump : public Job {
public:
Jump(std::vector<Data *> & vec, std::size_t my_indices)
: vec(vec), my_indices(my_indices) {}
virtual void run() {
for (std::size_t i = 0; i < vec.size(); ++i) {
if (i % NUM_THREADS == my_indices) {
vec[i]->counter++;
}
}
}
private:
std::vector<Data *> & vec;
std::size_t my_indices;
};
class Finish : public Job {
public:
virtual void run() {
pthread_exit(NULL);
}
};
void wait_for_jobs(int num) {
pthread_mutex_lock(&job_mutex);
while (jobs_completed < num) pthread_cond_wait(&job_cond, &job_mutex);
pthread_mutex_unlock(&job_mutex);
}
int main() {
std::cout << "Starting main programm" << std::endl;
pthread_t tid[NUM_THREADS];
for (int i = 0; i < NUM_THREADS; ++i) {
pthread_create(&tid[i], NULL, start, NULL);
}
std::cout << "Threads created" << std::endl;
std::vector<Data *> vec;
for (std::size_t i = 0; i < NUM_THREADS; ++i) {
vec.push_back(new Data());
std::cout << "Created counter at address: " << &vec.back()->counter << std::endl;
}
std::cout << "Vector initialized" << std::endl;
Loop l(vec);
pthread_mutex_lock(&job_mutex);
for (std::size_t i = 0; i < NUM_THREADS; ++i) {
work[i] = &l;
}
std::cout << "Added loop jobs" << std::endl;
pthread_cond_broadcast(&job_cond);
pthread_mutex_unlock(&job_mutex);
wait_for_jobs(NUM_THREADS);
std::vector<Jump *> jump_vec;
for (std::size_t i = 0; i < NUM_THREADS; ++i) {
jump_vec.push_back(new Jump(vec, i));
}
pthread_mutex_lock(&job_mutex);
for (std::size_t i = 0; i < NUM_THREADS; ++i) {
work[i] = jump_vec[i];
}
std::cout << "Added jump jobs" << std::endl;
pthread_cond_broadcast(&job_cond);
pthread_mutex_unlock(&job_mutex);
Finish f;
pthread_mutex_lock(&job_mutex);
for (std::size_t i = 0; i < NUM_THREADS; ++i) {
work[i] = &f;
}
pthread_cond_broadcast(&job_cond);
pthread_mutex_unlock(&job_mutex);
for (std::size_t i = 0; i < NUM_THREADS; ++i) {
pthread_join(tid[i], NULL);
}
}
-------------------------------------------------------------------------
This SF.net email is sponsored by: Splunk Inc.
Still grepping through log files to find problems? Stop.
Now Search log events and configuration files using AJAX and a browser.
Download your FREE copy of Splunk now >> http://get.splunk.com/
_______________________________________________
Valgrind-developers mailing list
[email protected]
https://lists.sourceforge.net/lists/listinfo/valgrind-developers
